
public class Test_Demol1 {
    public static void main(String args[]){
        //顺序结构学习：举例
        System.out.println("111");
        System.out.println("222");
        System.out.println("333");



        //if语句学习：
        //1.判断学生成绩：
        int score = 90;
        if(score >= 90){
            System.out.println("优秀");
        }else if(score >=80 && score <90){
            System.out.println("良好");
        }else if(score >=70 && score <80){
            System.out.println("中等");
        }else if(score >=60 && score <70){
            System.out.println("及格");
        }else if(score >=0 && score <60){
            System.out.println("不及格");
        }else{
            System.out.println("参数错误");
        }


        //判断一个数字是奇数还是偶数：
        int num = 10;
        if(num % 2 ==0){
            System.out.println(num + "是偶数");
        }else{
            System.out.println(num + "是奇数");
        }


        //判断一个数字是正数，负数，还是0：
        int number = -1;
        if(number > 0){
            System.out.println(number + "是正数");
        }else if(number == 0){
            System.out.println(number + "是零");
        }else{
            System.out.println(number + "是负数");
        }


        //判断一个年份是否为闰年：
        int year = 2000;
        if((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)){
            System.out.println(year + "是闰年");
        }else{
            System.out.println(year + "不是闰年");
        }

        int x = 20;
        if(x == 20);
        {
            System.out.println("你写错了");
        }

    }
}
